TW594967B - Method for recovering alignment mark - Google Patents

Abstract

A method for recovering an alignment mark is disclosed, by using focused ion beam (FIB) to remove metal layers and insulator layers covered on the alignment mark during manufacturing a metal-insulator-metal capacitor structure. Therefore, the cost, time, and manpower of recovering the alignment mark can be reduced.

Description

594967 V. Description of the invention (1) Technical field to which the invention belongs: The present invention relates to a method for reproducing an alignment mark (A1 ignment Mark), and particularly to a method using a focused ion beam (Focused Ion Beam; FIB) Method for reproducing alignment marks in metal-insulator-metal (MIM) capacitor structure. Prior technology: In the manufacturing process of semiconductor components, as the components become smaller and smaller, the mask pattern also shrinks. Therefore, in order to accurately transfer the mask pattern to the photolithography process, On semiconductor wafers, it is usually necessary to provide several alignment marks on the wafer for alignment of the photomask so that the photomask pattern is accurately copied to a desired position on the wafer. Metal layer-insulation layer-metal layer capacitors have a wide range of applications in semiconductor technology, such as radio frequency (Ra (jiFreqUency; rj?) Circuits, analog integrated circuits (Analog Integrated Circuits; Analog ICs), high power = micro Processor Units (Microprocessor Units; MPUs), and Dynamic Random Access Memory Cells (DKAM Cells), etc. The metal layer-insulation layer-metal layer capacitors are applied During the semiconductor manufacturing process, the alignment marks will be covered by opaque metal materials and cannot be used for alignment of the photomask. Therefore, the general practice is to use 疋 f metal layer-insulation layer-metal layer capacitors. After the layers of material are stacked, the material layer covered on the quasi-private β is removed to reproduce the alignment mark. The objective reproduction mark is a process such as lithography and etching to remove the alignment mark 5 Each layer of material until the alignment mark appears.

594967 V. Description of the invention (2) Figures to Figure 3 'Figures 1 to 3 are cross-sectional views showing a conventional reproduction alignment process. As shown in FIG. 1 'the substrate 10 has -groups of gold: the reed lilRi substrate 100 is further covered with a sequentially stacked dielectric layer 104, a layer i06, a dielectric layer 108, and The metal layer 110, wherein the metal layer " electrical layer 108, and the metal layer 11o constitute a metal layer-insulating layer_metal layer: capacity 112. Since the metal layer 106 and the metal layer 110 are opaque, they are placed on the metal layer u for the re-appearance of if 02. A layer of photoresist is applied on top to facilitate subsequent removal of each material layer covering the alignment mark 102. =, Performing the exposure and development steps on the photoresist layer 114 to remove the photoresist layer 114 of the alignment mark φ, and expose a part of the metal layer 110, thereby forming a region marked with a 〇2, such as Figure 2 shows the structure. After etching the area of the alignment mark 1 〇2 in 5 U 4, the photoresist layer 11 4 = was used to remove the exposed metal layer 110 and the metal layer in this part by using an anisotropic dry engraving technique. The dielectric sound, the metal layer 106, and the dielectric layer 104 are below 110. Among them, since the material ... the dielectric layer 104 and the alignment mark 102 are also impermeable to the material layer, the dielectric layer 104 is not required to be impermeable. Then, use wet stripping (we: ^ = 的 重 ^ 层 " I and expose the metal layer ：: 』In the invention; the structure formed now is shown in Figure 3. Ϊ: i ί ΐ ΐ: ί: When marking, the lithography and #lithography process are used to ^ quasi-private material layer, not only the procedure is too complicated, but also the process cost, time, and human burden. More on page 6 594967 V. Description of the invention (3) Therefore, in the reproduction method of the present invention, the #material layer removes the sub-beam to accurately mark the material on the surface. The other aspect of the present invention can be modified because the focus is lifted off the ground to improve the metallicity. The method of aligning marks, engraving, and copying. According to the present method described above when saving the process, at least including an alignment mark and including sequentially stacking the layer capacitors. The main purpose of the overlay is to focus. Since the hunting layer is adjusted to the required material layer, one of the effective weights is to focus the ion beam. Therefore, the purpose of the alignment is to provide a sub-beam which can effectively re-layer-insulation layer-Jinshan element structure. It ’s in that there is no need to strip the photoresist, and For the purpose, this chapter includes the following steps. The metal layer, insulation layer, and metal layer on the first substrate are covered by the metal layer. The second metal layer is marked with the second one. The use of a metal layer, a layer for light transmission, and a line of coating for the electrical layer and the layer to avoid the inventor's further steps: the dielectric layer of the substrate is at least focused on the electrical layer and the second layer is focused away from the second layer. The intermediary material is to provide an alignment mark which will cover the ion beam machines on the alignment mark, so that the focus can be removed and the overlay mark can be removed smoothly. A method of reproducing the alignment mark, mark Therefore, in addition to the use of photoresistors, which can be greatly accommodated in the application of semiconductor processes, power resources have been provided for a base, a surface, and a side, including the first and the first beamlet transfer. Layer, so it is easy to focus away from the photoresist, which can reduce the waste of a pair of materials, on which the metal layer is aligned with the standard stack, and the dielectric is removed, and the first sub-beam is used to reproduce the exposure and significantly lower. The manufacturing process becomes 0. The priority of the quasi-mark is that the substrate is on this substrate and -insulating layer-gold is marked, and one of the first gold layers and one is aligned with a metal layer as described above. Focusing the ion beam

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When removing the second metal layer, two persons, and one metal layer overlying the alignment mark, the first one above the alignment mark can be removed; the electrical layer =: I, Π does not remove the first dielectric layer, that is, The alignment mark can be displayed; the entire focal ion beam machine can make the focused ion beam accurately fall on each material layer being removed, and smoothly remove the layer above the alignment mark to make the alignment mark reappear . Embodiment: A method for reproducing an alignment mark 'uses a focused ion beam to remove a material layer covering the alignment mark. Therefore, the alignment lever a can be easily reproduced without additional process cost, time, and human load, so as to achieve the purpose of restoring the alignment mark to its alignment function. In order to make the narration more complete and complete, you can refer to the following description and cooperate with the diagrams in Figure 4 and Figure 5. , «Yuexiang ..., Figure 4, Figure 4 is a schematic cross-sectional view showing the process of reproducing the alignment mark in a preferred embodiment of the present invention. First, a semiconductor substrate 20 0_ is provided. One surface of the substrate 200 has at least one set of alignment marks 202, which are aligned when i and the component layout pattern are transferred, so that the component layout pattern can be finely reproduced. To the desired position on the substrate. The substrate 200 may be a semiconductor wafer, for example. In addition, on the substrate 200, a dielectric layer 204 covers the surface of the alignment mark 202 and the substrate 200 where the alignment mark 200 is located, and the dielectric layer 204 has The metal layer 206, the dielectric layer 208, and the metal layer 210 are sequentially stacked. Among them, the metal layer 206, the dielectric layer 208, and the metal layer 210 form a metal layer-insulation layer-metal layer type capacitor 212. Since the metal layer 210 and the metal layer 206 are opaque materials, the alignment mark 202 is opaque

594967 V. Description of the invention (5)-The metal layer 210 and the metal layer 206 are masked 'and cannot provide the alignment function that the alignment mark go? Should have. In order to reproduce the alignment mark 202, the present invention uses a focused ion beam machine (only the ion beam projector 21 is shown) to provide a high-energy focused ion beam 216 to remove the alignment mark 2. 2 the material layer above. At this time, the ion beam projection $ 214 is adjusted so that the focused ion beam 216 emitted by the ion beam projector 214 can surely land on the area above the alignment mark 202. The ion beam projector 214 is then used to project the focused ion beam 216 onto the metal layer 21 / above the alignment mark 2 02. The ion beam projector 214 is controlled to move back and forth in the direction 218 and the direction 220, so that the focused ion beam 2 1 6 can be repeatedly projected onto the material layer above the alignment mark 202, and the alignment mark M is sequentially removed. ? On the metal layer 210, the dielectric layer 208, and the metal layer 206. When removing the material layer above the alignment mark 202, the current and voltage of the focused ion beam machine can be adjusted according to the thickness and material parameters of each material layer to adjust the ion flux of the focused ion beam 21 6 (Flux ). In this way, the removal depth and removal rate of each material layer can be effectively controlled. Among them, when using the focused ion beam 2 16 to remove each material layer above the alignment mark 202, the ion beam projector 214 can be moved back and forth as described above, and the substrate 2 can also be selected to be moved back and forth. That is, as long as the focused ion beam 216 can be moved over the material layer of the entire area above the alignment mark 202, the present invention is not limited thereto. Because the dielectric layer 208 and the dielectric layer 204 are made of a light-transmitting material, in addition, there is no opaque material layer between the dielectric layer 204 and the alignment mark 202. Therefore, the dielectric layer 204 above the alignment mark 202 cannot be completely removed, as shown in FIG. 5,

Page 9 594967 V. Description of the invention (6) It is not even necessary to remove the dielectric layer 204. The source gas of the focused ion beam 216 may be, for example, inert ammonia or the like.时 When using the focused ion beam 216 to remove each material layer of the alignment target, special active gas can also be added, such as two fossils (Si〇2), moth (l2), fluoride gas (M ), And water vapor selection ratio CSelectiviW thousand degrees, or increase (decrease) to remove Ϊ 1 find ϊ:: Ϊ is 'covered above the alignment mark 202 in this embodiment', "" is made of metal Layer-insulating layer_metal layer of the capacitor 212. However, the present invention can be used to remove the structure composed of an opaque material layer or a light-transmitting material layer covering the alignment mark 202. For example, the material is noted above. = Can only be constructed by sequentially stacked dielectric layers and metal layers I: ^ Not necessarily a metal layer-insulation layer-metal layer capacitor structure. In summary, one of the advantages of the present invention is that the machine can make The focused ion beam accurately falls on the alignment mark; i ::: has the purpose of removing the m-synthetic order over the alignment mark and reappearing the alignment mark. The present invention also has the advantage that: Focusing the ion beam can effectively reproduce the record, so that not only can greatly improve the overlap table between two = and further improve The advantages of the process reliability and product and layer of the present invention are that because the steps of coating photoresist, photoresist and development, and photoresist removal can be omitted, the process cost can be reduced, and the process can be saved. Time, but also avoid waste of human resources

594967 V. Description of the invention (7) As understood by those familiar with this technology, the above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of patent application for the present invention; Equivalent changes or modifications made under the spirit of disclosure should be included in the scope of patent application described below.

594967 Schematic illustration of the preferred embodiment of the present invention has been described in more detail in the preceding explanatory text with the following figures, where: Figures 1 to 3 show the conventional process of reproducing the alignment mark 4 is a schematic cross-sectional view showing a process for reproducing an alignment mark according to a preferred embodiment of the present invention; and FIG. 5 is a reproduced alignment mark showing a preferred embodiment of the present invention. Later section of the structure. Description of drawing numbers: 100 substrate 102 alignment mark 104 dielectric layer 1 06 metal layer 108 dielectric layer 110 metal layer 112 capacitor 114 photoresist layer 200 substrate 202 alignment mark 204 dielectric layer 2 0 6 metal layer 208 Dielectric layer 210 Metal layer 212 Capacitor 214 Ion beam cast 216 Focus ion beam 218 Square 220 direction

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Claims (1)

594967 VI. Application Patent Scope 1. A method for reproducing an alignment mark (A 1 ignment Mark), at least the sentence includes: A substrate is provided, wherein the substrate includes at least one alignment mark on a surface of the substrate And the substrate includes at least a layer of opaque material covering the surface of the substrate and the alignment mark; and using a focused ion beam (FIB) to remove the cover over the alignment mark A layer of opaque material to expose the alignment mark. 2. The method for reproducing the alignment mark according to item 1 of the scope of patent application, wherein the material of the opaque material layer is metal. 3. The method for reproducing the alignment mark according to item 1 of the scope of the patent application, wherein the source gas of the focused ion beam includes at least an inert gas. 4. The method for reproducing the alignment mark according to item 1 of the scope of the patent application, wherein the source gas of the focused ion beam includes at least argon (Ar). 5. The method for reproducing the alignment mark according to item 1 of the scope of the patent application, wherein the source gas of the focused ion beam includes at least helium (He). 6 · The method of reproducing the alignment mark as described in item 1 of the scope of the patent application, wherein when the focused ion beam is used to remove the opaque material layer above the alignment mark, it is more useful to include the introduction of an active gas (Active Gas) method to improve material removal rate, selection ratio, and surface flatness. Page 13 594967 VI. Patent Application Range 7. The method for reproducing the alignment mark as described in item 6 of the patent application range, wherein the active gas is silicon dioxide (Si 02). Among its legal parties, ~ 1g of the Jigu D standard is described in item 6 ο Article} 2 Circumstances I Fan private interest is a special body, please apply for air, such as living. Hai 8 I 9. As described in item 6 of the scope of patent application A method for reproducing the alignment mark, wherein the active gas is a gasification gas (X e F2). 10. The method for reproducing the alignment mark as described in item 6 of the scope of the patent application, wherein the active gas is water vapor. 11. A method for reproducing an alignment mark, at least comprising: providing a substrate, wherein the substrate includes at least one alignment mark on a surface of the substrate, and the substrate includes at least sequentially stacked layers A light-transmitting material layer covers the surface of the substrate and the alignment mark and an opaque material layer; and using a focused ion beam to remove the opaque material layer covering the alignment mark, Thereby, the alignment mark is exposed. 1 2. The method for reproducing the alignment mark as described in item 11 of the scope of patent application, wherein the material of the opaque material layer is metal. Page 14 594967 VI. Scope of patent application 1 3 · The method of reproducing the alignment mark as described in item 11 of the scope of patent application, wherein the material of the transparent material layer is a dielectric material. 14. The method for reproducing the alignment mark according to item 11 of the scope of the patent application, wherein the source gas of the focused ion beam includes at least an inert gas. 15. The method for reproducing the alignment mark according to item 11 of the scope of the patent application, wherein the source gas of the focused ion beam includes at least argon. 16. The method for reproducing the alignment mark as described in item 丨 丨 of the scope of patent application, wherein the source gas of the focused ion beam includes at least helium. 17. The method for reproducing the alignment mark as described in item 11 of the scope of the patent application, wherein the focused ion beam is used to remove the opaque t material layer covering the alignment mark, and at least includes removing A portion of the light-transmitting material layer above the alignment mark. The ion beam removal covers the removal rate, selectivity, and flatness of the material covering the alignment mark above the alignment mark. The method is to change it as described in item 8. In the alignment standard, the active gas system is selected from the group consisting of sulphur dioxide and hard: its xenon tritium, and water Page 15 594967 VI. Scope of patent application A group of steam. 2 0. A method for reproducing an alignment mark, including at least: providing a substrate, wherein the substrate includes at least one alignment mark on a surface of the substrate, and the substrate includes at least a sequential stack A first dielectric layer and a metal layer-insulation layer-metal layer (MIM) capacitor cover the surface of the substrate and the alignment mark, and the metal layer-insulation layer-metal layer capacitor includes at least Sequentially stacking a first metal layer on the first dielectric layer, a second dielectric layer, and a second metal layer; and using a focused ion beam to remove the first metal layer overlying the alignment mark Two metal layers, the second dielectric layer, and the first metal layer. 21. The method for reproducing the alignment mark according to item 20 of the patent application, wherein the source gas of the focused ion beam includes at least an inert gas. 2 2. The method for reproducing the alignment mark according to item 20 of the scope of the patent application, wherein the source gas of the focused ion beam includes at least argon. 2 3. The method for reproducing the alignment mark according to item 20 of the scope of patent application, wherein the source gas of the focused ion beam includes at least helium. 2 4. The method for reproducing the alignment mark according to item 20 of the scope of the patent application, wherein the focused metal ion beam is used to remove the second metal layer, the second dielectric layer, and the second dielectric layer. When the first metal layer is included, at least Page 16 594967 VI. Scope of Patent Application Excluding a part of the first dielectric layer above the alignment mark. 25. The method of reproducing the alignment mark as described in item 20 of the scope of the patent application, wherein the focused ion beam is used to remove the second metal layer, the second dielectric layer above the alignment mark, and When the first metal layer is used, a method including introducing an active gas can be used to improve the material removal rate, selection ratio, and surface flatness. 2 6. The method for reproducing the alignment mark according to item 25 of the scope of the patent application, wherein the active gas is silicon dioxide. 2 7. The method for reproducing the alignment mark as described in item 25 of the scope of patent application, wherein the active gas is iodine. 2 8. The method for reproducing the alignment mark as described in item 25 of the scope of patent application, wherein the active gas is xenon fluoride. 2 9. The method of reproducing the alignment mark as described in item 25 of the scope of patent application, wherein the active gas is water vapor. Page 17